Hi Simon, On Wed, Feb 8, 2012 at 6:12 PM, Simon Glass <s...@chromium.org> wrote:
> Also make sure that the I-Cache is on as early as possible. Relocation > is done with the d-cache off so is slow. Takes about 40ms for me from Have a close look at the latest x86 patches (not yet pulled into mainline) as an example of how this does not need to be the case. The sequence I now use is: 1) Initialise 'Cache-As-RAM' (CAR) - Cache cannot be used to cache SDRAM, otherwise the Stack and Global Data get trashed 2) Create Stack and Global Data in CAR 3) Initialise SDRAM 4) Create a new stack in SDRAM 5) 'Pivot' U-Boot - Move stack from CAR to SDRAM (U-Boot still running in Flash) 6) Copy Global Data into SDRAM (adjust the global data pointer to point to the in-RAM copy) 7) CAR is no longer used - Enable caching of SDRAM 8) Copy U-Boot to RAM 9) Perform relocation adjustments to in-RAM copy 10) Jump to in-RAM copy 11) Continue initialisation > memory, but we do have things which can speed it up. But d-cache > matters more than just about anything. Now it may be the case (going by Wolfgang's comments) that some amount of high-memory needs to be reserved, and the amount to be reserved is not known until environment has been read. So there may be a need to put the initial in-RAM stack and global data somewhere 'safe' while high- memory space is calculated and U-Boot copied into RAM. Stack and global- data can then be moved again (stack probably doesn't need moving, just re-initialised at a new location) just below U-Boot. This would still be a lot cheaper than copying U-Boot with D-Cache off Regards, Graeme _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot